09:03 pm - Ding! (dum) Ding! (dum)

Something in or behind the vacant house next door, or between
that house and the (also vacant) one just beyond it, has been chiming
for the past few hours. In most of my house it sounds like an
UPS complaining -- I can only hear the higher, louder tone --
with no clear sense of where it is. On the landing upstairs or
in the back room on the third floor, both tones are audible and
it sounds a lot like the noise some cars make when you leave
the lights on or the key in the ignition.

I wonder what's making the noise, but I don't wonder quite
enthusiastically enough to climb out on the roof to get closer
for more clues.